A combiner receives two input signals and generates a combined output signal. The frequency components of the output signal are generally similar to the frequency components of the input signals. A combiner typically has a loss of gain (in other words an attenuation).
When combining very low level signals, there is a need to amplify the combined signals before further processing is performed. Hence, there is typically a need for an amplifier stage. In wide band applications, the combiner stage and the amplifier stage must be designed to respond to the entire frequency band of operation. These are difficult design requirements.
It is difficult to fabricate a wide band combiner on a die for use as an integrated circuit (IC). It is even more difficult to fabricate an ultra wide band active combiner on a die having gain across a frequency band that spans from direct current (DC) up to a frequency in excess of 20 GHz. The present invention addresses such a combiner.